A murdered Red Cross worker and her ex-boyfriend suspected of killing her both worked for the Home Office, it emerged today.

Police were searching the grounds of a stately home this week for Martin Collett, 35, a former briefing manager for Labour home secretaries David Blunkett and Charles Clarke.

The manhunt was launched after the body of his ex-girlfriend, Angela Hoyt, 34, was found at her home in Glebeland in Hatfield, Hertfordshire, at around 5.20pm on Tuesday.

Ms Hoyt worked as a junior member of the Home Office media team around the same time Mr Collett was employed in his private office role at the department.

A Home Office spokesman said: "They both did work in the Home Office."

Ms Hoyt is believed to have died some time between May 22 and May 24 - just days after she made a report of harassment to Hertfordshire Police.

The Independent Police Complaints Commission (IPCC) has now launched a probe into the force's response to this complaint.

IPCC commissioner Sarah Green said: "The IPCC is independently investigating Hertfordshire Police's response to a report of harassment made at Hatfield Police Station on the afternoon of May 20 2011.

"The woman who made the allegation, Angela Hoyt, was subsequently murdered and there is an ongoing police operation to trace her former partner.

"Therefore at this stage we will not be issuing any further information, and I would encourage any members of the public who can help the police find him to contact them immediately."

Around 30 specialist officers scoured the grounds of Hatfield House in Hertfordshire on Friday after receiving information about a man seen in the area.

Detective Chief Inspector Mark Ross of the Bedfordshire and Hertfordshire Major Crime Unit said: "Understandably this is an extremely difficult time for Angela's family and it is vitally important we trace Martin Collett as soon as possible."

Ms Hoyt's family have paid tribute to the "very ambitious and driven girl".

They said in a statement: "She had a passion for human rights and wanted to use her work to help improve the lives of those less fortunate. She had strong opinions and convictions."

Ms Hoyt, who was born in Windsor in Ontario, Canada and moved to the UK in 1999, had recently returned from a three-month role in Pakistan as part of her work with the Red Cross.

She had been working as a public affairs and communications adviser with the International Committee of the Red Cross since February 2008.

She is survived by her parents, Barb and Dwight Hoyt, her identical twin sister Ami Watanabe and Ami's husband Garry, and niece and nephew Tori and Kai.

Officers have not yet released any further details about how she died.